Starting from the 1920s, the Museum of Society and Economy in Vienna produced an innovative technique in the graphic representation of social statistics. The authors of this method (Isotype), Marie and Otto Neurath, aimed at creating an accessible medium for a general audience, including illiterates and factory workers, in order to popularize the statistical treatment of social matters. They developed Isotype for the production of exhibition material and worked for its widespread use in teaching and publishing. This article analyses Isotype's philosophical background in the Vienna Circle's logical empiricism. The graphic language of Isotype will be examined in the framework of the international auxiliary language movement, of which two examples (Basic English and Interglossa) will be introduced, showing their common philosophical influences and structural traits.

Otto Neurath and the Vienna Circle

      Logical empiricism emerged as an anti-metaphysical movement in the interwar period. Adopted by the Vienna Circle as an up-to-date version of the Enlightenment, the movement constructed its intellectual identity around a strong opposition between metaphysics and the scientific worldview. Most logical empiricists were freethinkers, social-democrats or socialists, although political analysis of metaphysics was more apparent in the left wing of the circle (and arguably a somewhat peripheral concern for logical empiricists), carried out chiefly by Rudolf Carnap, Hans Hahn, Otto Neurath, Philipp Frank and Edgar Zilsel. These members of the circle saw in metaphysics an irrational form of expression rooted in conservatism and attachment to the past social order. The logical empiricist program may be regarded as a polemical response to metaphysical trends associated with the right-wing policy of its time [1]. For logical empiricists, metaphysics excludes rational discussion on the basis of a neutral common ground due to its idiosyncratic and uncritical language. As opposed to this, the scientific worldview identifies itself as transformative and progressive, if not revolutionary. Its intercultural validity comes from its empirical basis, which constitutes a universal common ground for communication and decision-making. Inclusivity and the democratic accessibility of empirical discourse were the reasons why the Vienna Circle represented empiricism in philosophy, opposing sectarian philosophical stances and privileging informed mutual cooperation on a scientific basis.
      Verifiability is the logical empiricist criterion of signification. Logical empiricists emphasized a demarcation between meaningful and meaningless statements in order to identify and discredit metaphysical statements. The empiricist criterion of meaning posits that a legitimate proposition should be reducible to its empirically verifiable truth-conditions. This excludes statements about God and other supernatural entities as well as any speculation which falls outside the domain of public experience (e.g. introspective statements relating mystical experience). Metaphysical, religious and moral terms are rejected because of the local limits of their validity. Since they are confined to a specific culture, these are often difficult, sometimes impossible, to translate, as opposed to scientific argument, which is, for Neurath, common to all nations [2].
      From the verificationist theory of meaning follows the main thesis of Neurath's physicalism: the translatability of scientific statements into statements of daily experience, following the reducibility of the latter to “protocol-statements” (Neurath 1932/33) relating basic sense-observations. This assumption forms the basis of the physicalist pedagogy, in the framework of which Isotype, the graphic language for social statistics, was designed. As the language of intersubjective experience, the “physicalist jargon” includes not only scientific terms in a strict sense, but also more imprecise concepts of everyday language referring to physical objects that we talk about in ordinary daily life, like houses, trees, mountains or stars. Neurath's pedagogy is centred on these concepts (Ballungen, Neurath 1932/33), low in precision but high in stability, as a bridge between the language of everyday experience and the highly precise and sophisticated language of science. Indeed, as the expression of collective experience, such expressions are not only useful for verification of scientific theories: they also have a crucial role in ensuring continuity across theoretical changes, as well as in interdisciplinary communication and science teaching. The reason for this privileged status of Ballungen is their relative stability across succeeding generations and different civilizations.
      Physicalist pedagogy starts from the learner's own realm of experience: time will be treated in terms of visible indications on a clock, heat in terms of data from thermometers, life in terms of behaviour of organisms. This technique is called by Neurath “humanization,” as opposed to popularization which consists in paraphrasing scientific theories in simpler terms, without relating them to familiar experience. A gradual translation from the simplest concepts into more complicated ones has a very important psychological advantage: it keeps the uninitiated student from possible discouragement, since most learners with lower instructional backgrounds are intimidated when confronted with abstract language full of technical terms. Humanization following the principles of physicalism overcomes the inferiority complex which often inhibits people's learning capacities in adult education. That's why Neurath recommends avoiding general discussions about abstract entities at the start, preferring explanations in terms of observable behaviour instead.
      Neurath's own teaching experience took place mostly in adult education. His audience was a general public, usually workers with little educational background and limited literacy. This restriction brought him to consider the use of alternatives to verbal language in education. Neurath observes that linguistic divisions do not only operate on a transnational level. Not only do different nations speak different languages, but even inside one language community intellectual jargon often remains inaccessible to lower classes. Furthermore, people attending evening classes are usually tired after a hard day working in a factory or office, and this situation diminishes their ability to focus on verbal explanations and fully benefit from them. Compared to spoken or written language, well-designed pictures have a more striking effect on the viewers. Even though their expressive power is limited compared with words, they are easier to remember and more pleasant to observe and discuss. Neurath claims that pictures make a relatively egalitarian aid for instruction, since people tend to react to them in similar ways, and different levels of literacy or familiarity with sophisticated language do not have a divisive effect on the viewers [3]. This need for a graphic medium tailored for universal communication, especially in the framework of mass education, motivated Neurath's work in visual pedagogy.